Richard Bannister has released a new version of fMSX for Mac OS X as well as an updated version of his Emulator Enhancer. The fMSX code has been synchronized with v3.5 of the core source code, which apparently involved a considerable amount of rewriting. Furthermore, some more configuration options were added to the Preferences and the shareware prompt does not appear during the first five minutes of program execution.
Relevant link: fMSX v3.5.1 for Mac OS X